Physicists at Technische Universität Kaiserslautern in the team of Professor Dr. Herwig Ott have succeeded for the first time in directly observing collisions between highly excited atoms, so-called Rydberg atoms, and atoms in the ground state. Particularly interesting is that they can precisely identify the energy states of the individual atoms, which was impossible until now. The researchers have developed a custom microscope for this purpose, with which they were able to directly measure the momenta of the atoms. The processes observed are important for understanding interstellar plasma and ultracold plasmas generated in the laboratory. The study was published in the renowned journal Nature Communications.